Small area maps can be loaded into the following Garmins:- the new Etrex, the Dakota, the Oregon and the Montana by using the Garmin custom map feature. see www.garmin.com/us/products/onthetrail/​custommapswww.garmin.com/us/products/onthetrail/​custommaps here's a Q&A about this method https://help.openstreetmap.org/questions/27269/is-there-a-simple-way-to-create-a-garmin-custom-map-kmz-type-from-osm-data

Small area maps can be loaded into the following Garmins:- the new Etrex, the Dakota, the Oregon and the Montana by using the Garmin custom map feature. see www.garmin.com/us/products/onthetrail/​custommaps